SUMMARY (See instructions): The Flow Cytometry Shared Resource (FACS-SR) provides AECC investigators with technologies required for fluorescence-based cell analysis and sorting. A broad range of research in a large proportion of AECC associated laboratories is supported by the FACS-SR, with connections to virtually all AECC programs and training activities. The instruments required for flow cytometry and cell sorting are intricate and expensive, making this a logical resource to provide through a centralized facility. In addition, cell sorting presents complex issues in biocontainment, requiring specialized laboratory space and highly trained personnel for proper management. The organization of these resources within the FACS-SR has proven to be an extremely efficient approach to creating a well supervised, quality controlled, cost effective and safe environment for FACS-based analysis and cell sorting. Since the last CCSG review in 2007, the FACS-SR has undergone major expansion to add new capabilities as well as a needed increase in the capacity for all services. Substantial additional laboratory space has been added, including rooms that are specially configured for enhanced BSL-2 work involved with sorting of primary human cells or potentially infectious material. Work performed to a great extent by AECC members has driven technology development in the FACS-SR, and supported multiple successful NIH Shared Instrumentation Grants over the past five years. This, along with substantial ongoing institutional support, has led to the acquisition of major new equipment and expansion of the resources and services provided by the FACS-SR. Three new cell sorters have been added to the facility since the last competing renewal, enabling accommodation of the growing need for this resource. Both Beckman-Coulter MoFlo and BD FACSAria sorters are operated by the facility, providing an extraordinarily advanced and versatile range of cell sorting applications. In addition, several analytical flow cytometers have been added to the facility's inventory, and facility staff has been increased to achieve maximum utilization of the instrumentation. The FACS-SR has also been highly successful at introducing novel technologies to AECC investigators in recent years, such as laser scanning cytometry and newly derived fluorescent proteins with unique spectral properties. The FACS-SR staff provides training on all the instruments, as well as consultation to assist with experimental design and instrument selection. A well established administrative structure ensures orderly management of facility operations and efficient delivery of services at the lowest possible cost.